Suppose three coins are lined up, touching each other.[br][br]We hold one of the end coins still.[br]We rotate the middle coin around the fixed coin, without slippage.[br]We keep the third coin in contact with the second, so it too turns without slippage.[br][br]If the turning coins go once around and end up in their original positions, how many times do they rotate?[br][br]The classic version of this puzzle uses only two coins.[br]The answer in both versions depends on the relative sizes of the coins.

Suggestion: Don't touch the diagram below until you've thought about the problem a little.[br][br]I've tried to limit the diagram so that it can't quite show you the answer, but even so, I was very surprised by what it showed me.[br][br]If I was a little less scrupulous, I might modify this to make a rotation version of an [url=https://www.geogebra.org/m/bMETTpEJ]area rearrangement puzzle[/url].

In this version, use sliders a, b, and c to set each circle's circumference.[br][br]Slider n sets the number of color bands that each circle is divided into.[br]If you're just getting started, my advice is to set a, b, and c how you like them and then either leave n at 1 or the maximum value on its slider, whichever you prefer.[br][br]Other values of n might cause problems. Checking the "override color guard" box makes these problems more likely. Can you explain the glitch?